Galaxy S7 Edge can't send or receive MMS with WiFi enabled

For the last few days my phone has been unable to send MMS while WiFi is enabled. I haven't changed any settings and there were no updates to anything as far as I am aware. I'm aware that mobile data has to be enabled in order to send a multimedia message, but mine is always on. I'm forced to disable my wireless connection every time I want to send a group message or picture. It's also not an APN issue as I have checked the settings myself and checked with my service provider. It's an unlocked model so there is no chance of WiFi calling interfering. Any ideas as to what is causing this issue?